Initiator for polymerizing and/or cross-linking polyorganosiloxanes with cross-linkable functional groups, corresponding compositions and their uses

ABSTRACT

The invention relates to a heat-activated initiator for polymerising and/or cross-linking polyorganosiloxane-type monomers, oligomers and/or polymers with organofunctional groups, comprising a boron derivative of formula (I): (A)xB(R&#39;)y, wherein the symbols R&#39; are the same or different and represent an alkyl or alkenyl radical in C1-C12, an alkoxy radical in C1-C12, a phenyl radical substituted by at least one electroattractor element, an aryl radical containing at least two aromatic rings such as biphenyl, naphthyl, optionally substituted by at least one electroattractor element, especially a halogen atom (particularly fluorine), or an electroattractor group, especially a CF3, NO2, CN group; and a radical -C2H4-Si(Q)3 with the symbols Q being the same or different and representing an alkyl or alkoxy group in C1 to C10 or a siloxane oligomer with less than 10 silicon atoms. The invention also relates to a corresponding cross-linkable composition and to the uses thereof.

The present invention relates to the field of initiation of reactionsfor polymerising and/or cross-linking polyorganosiloxane-type monomers,oligomers and/or polymers containing reactive functional radicalscapable of forming intra- and inter-catenary bridges so as to obtain acorresponding matrix.

More particularly, its main aim is to provide new initiators which willlead to these matrices.

This type of matrix is of particular interest for the preparation ofmultiple compositions such as dental materials, adhesives, sealants,jointing products and adhesive finishes.

The applications targeted more particularly by the invention are the useof compositions for the preparation of dental compositions such asdental prostheses or dental restoration materials and of compositions ofthe non-adhesive coating type used, in particular, to produce coatingson objects such as solid articles or substrates, in particular papersubstrate, fabric, polyester or polyolefin type polymer film, aluminiumsubstrate and/or metal substrate such as tin plate.

More precisely, the present invention relates to new initiatorscontaining at least one boron derivative for the initiation and progressof resin or polymer forming reactions, starting from substrate derivedfrom polyorganosiloxane-type monomers, oligomers and/or polymers withreactive organofunctional groups.

The reactions more particularly concerned are those in which agents actas direct promoters of the inter- and/or intra-catonary bonds In thepresent case, these reactions are initiated by heat activation.

In the present description, the resins and polymers obtained areprepared from polyorganosiloxane-type monomers, oligomers and/orpolymers and contain, in their structure, organofunctional groups, forexample of the epoxide, oxetane, dioxolane and/or alkenylether type,which react after activation of the initiators according to theinvention described hereinafter. In addition organic monomers, oligomersand/or polymers which may be added to the polymerisation mediumcontaining the aforementioned species may also be used.

The present invention also relates to compositions containing the basicmaterials such as cross-linkable polyorganosiloxane-type monomers,oligomers and/or polymers, the initiators described hereinafter andoptionally one or more additives selected from those generally known inthe applications for which these compositions are intended.

The initiators generally used to initiate the formation of resins orpolymers on the basis of the aforementioned polymerisation and/orcross-linking of organosiloxane substrates may be divided into threecategories, depending on their mode of activation. This mode ofactivation may in fact be thermal, photochemical or by an electron beam.

Conventionally, the initiator used, which is generally a cationicphotoinitiator, releases a strong acid under irradiation duringphotochemical cross-linking such as UV radiation This strong acidcatalyses the cationic polymerisation reaction of the functional groups.Initiators of this type are described, in particular, in EP-0 562 897.The initiating salts in that patent represent significant technicalprogress over the formerly known initiators of the onium salt ororganometallic complex type, and in particular over those of which theanion of the initiating salt is SbF₆— which is one of the only oneswhich has the correct performance but which poses serious problemsinfuse owing to the presence of heavy metals.

Thermal cross-linking, for its part, necessitates very high temperaturesgenerally higher than 150° C. to trigger cross-linking. This second typeof initiator is used, in particular, to cross-link silicones such asthose described hereinafter (S1 to S15) in a thin layer and for epoxideor oxetanes.

One of the main aims of the present invention is specifically to proposenew heat-activated initiators for triggering the cross-linking ofpolyorganosiloxane-type monomers, oligomers and/or polymers withfunctional groups at a temperature lower than 150° C. and preferablylower than 100° C., or even substantially at ambient temperature.

More particularly, the present invention relates firstly to aheat-activated initiator for polymerising and/or cross-linking monomers,oligomers and/or polymers with organofunctional groups, comprising aboron derivative of formula (I)

 (A)_(x)B(R′)_(y)  (I)

wherein

the symbols R′ are the same or different and represent

a linear or branched C₁-C₁₂, preferably C₁-C₈ alkyl or alkenyl radical,optionally substituted by at least one electron-withdrawing element, inparticular a halogen atom (more particularly fluorine) or anelectron-withdrawing group, for example the CF₃, NO₂, CN groups,

a linear or branched C₁-C₁₂, preferably C₁-C₈ alkoxy radical, optionallysubstituted by at least one electron-withdrawing element, in particulara halogen atom (more particularly fluorine) or an electron-withdrawinggroup, for example the CF₃, NO₂, CN groups,

a phenyl radical substituted by at least one electron-withdrawingelement, in particular a halogen atom (more particularly fluorine) or anelectron-withdrawing group, for example the CF₃, NO₂, CN groups,

an aryl radical containing at least two aromatic rings such as biphenyl,naphthyl, optionally substituted by at least one electron-withdrawingelement, in particular a halogen atom (more particularly fluorine) or anelectron-withdrawing group, for example the CF₃, NO₂, CN groups,

a —C₂H₄—Si(Q)₃ radical with the symbols Q being the same or different asrepresenting a C₁ to C₁₀ alkyl or alkoxy group or a siloxane oligomerwith less than 10 silicone atoms, substituted, if necessary, by aradical of formula B(R′)₂ with R′ as defined above or

two R′ groups may be bound to one another so as to form, with the boronatom to which they are bound, a cycle containing 5 or 10 atoms whereinsaid cycle may be saturated, unsaturated, bridged or aromatic and maycomprise one or more heteroatoms selected from oxygen, nitrogen andboron atoms, wherein the boron atom present in said cycle may itself besubstituted by a radical as defined for A or R′ in general formula I,

the symbols A are independent of one another and represent:

a hydrogen atom

a halogen atom or

a hydroxyl radical,

x represents 0 or the integer 1 or 2 and y represents an integer 1, 2 or3 wherein the sum of x+y is equal to 3 and its solvated forms.

The initiators according to the invention are generally very hygroscopiccompounds. Consequently, these compounds may be found in the form of amixture between the compound as defined in general formula I and itsvarious hydrated form(s). Similarly, when this initiator is formulatedwith a solvent, the formation of solvated derivatives is observed. Thisphenomenon can be observed with aprotic solvents such as ethers, estersand silicones or protic solvents such as alcohols, carboxylic acids,silanols, amines, thiols, water or mixtures thereof.

Consequently, the present invention also extends to these solvatedforms.

The new initiators are of particular interest in terms of reactivityinsofar as they are active at low concentrations and advantageouslynecessitate only small amounts of energy to carry out cross-linking. Infact, they may be activated at a temperature lower than 150° C.,preferably lower than 100° C., or even at ambient temperature.

The initiators according to the invention may also be associated with aconventional initiator such as a cationic photoinitiator. This isparticularly advantageous in terms of profitability insofar as it isthus possible significantly to reduce the effective quantity ofconventional initiator. Furthermore, cross-linking and/or polymerisationare totally completed.

It has accordingly been found that the claimed initiators areparticularly advantageous in terms of profitability and cost forindustrial processes.

More preferably, the symbols R′ of general formula (I) are selected soas to give the boron atom to which they are bound adequate sterichindrance to give it adequate protection from oxidation and/or hydrationphenomena. In this instance, the initiators of general formula (I) inwhich at least one of the symbols R′ and preferably at least two of themrepresent a phenyl or aryl radical are of particular interest.

Similarly, it is advantageous that the symbols R′ are substituted and,in particular, by electron-withdrawing elements and/or groups so as togive the boron atom electronegativity which is compatible with itselectrophilic properties. Initiators of general formula I which thesymbols R′, together with the symbols A contribute to a σ_(p) at leastequal to that of 3 (C₆H₄F) radicals have accordingly been found to beparticularly effective.

Particularly preferred according to the invention are initiatorscorresponding to general formula (Ia)

in which

n represents an integer between 1 and 3 and m an integer between 0 and 2wherein the sum of n and m is equal to 3,

the symbols Y are the same or different and represent

a) a hydrogen atom,

b) a hydroxyl group,

c) a halogen atom,

d) a linear or branched C₁-C₁₂, preferably C₁-C₈ alkyl or alkenylradical, preferably substituted by at least one electron-withdrawingelement such as a halogen atom and in particular a fluorine atom,

e) a linear or branched C₁ to C₁₂, preferably C₁ to C₈ alkoxy radical,preferably substituted by at least one electron-withdrawing element suchas a halogen atom and in particular a fluorine atom,

f) a —C₂H₄—Si(Q)₃ wherein Q represents a C₁ to C₁₀ alkyl or alkoxy groupor a siloxane oligomer with less than 10 silicone atoms, if necessarysubstituted by a radical of formula B(R′)₂ wherein R′ is as definedabove, or

g) two groups Y may be bound so as to form, with the boron atom to whichthey are bound, a C₅ to C₁₀ cycle wherein said cycle may be saturated,unsaturated, bridged and/or aromatic and may comprise one or moreheteroatoms selected from the oxygen, nitrogen and boron atoms, whereinthe boron atom present in said cycle can itself be substituted by aradical as defined for Y in general formula (Ia) and

the symbols X′ are the same or different and represent

a halogen atom, preferably a fluorine atom,

a linear, branched, mono- or polycyclic, saturated, unsaturated oraromatic C₁ to C₁₂, preferably C₁ to C₈, hydrocarbon radical preferablysubstituted by at least one electron-withdrawing element such as ahalogen atom and in particular a fluorine atom or a linear or branched,mono-, poly or perhalogenated C₁ to C₁₂, preferably C₁ to C₈, alkylradical, in particular with fluorine as halogen atom, and

the indices p are the same or different and represent an integer between0 and 5, preferably with at least one of the symbols p being greaterthan 3 and more preferably equal to 5.

The initiators of general formula (Ia) in which Y corresponds todefinitions a), b), c), d) and e) are of particular interest.

The following compounds, in particular, may be mentioned as examples ofthe claimed initiators:

The initiators according to the invention may be used in the form inwhich they emerge from their preparation process, for example in solidor liquid form or in solution in at least one appropriate solvent, inmonomer, oligomer and/or polymer compositions which are intended to bepolymerised and/or cross-linked. In the scope of the invention, the termsolvent covers products which make solid initiators soluble and productswhich dilute liquid or solid initiators.

Preferably, the initiators are generally used in solution in a solvent.The proportions by weight of initiating agent(s) on the one hand and thesolvent on the other hand are between 0.1 and 99 parts per 100 parts ofsolvent and preferably 10 to 50 parts.

This initiator solution is therefore used to prepare a bath with thecross-linkable monomers, oligomers and/or polymers with functionalgroups such that the concentration of the initiator or initiatorspresent is between 0.01 and 5% by weight in said bath and preferablybetween 0.05 and 0.5%.

The solvents which may be used for the initiators are very numerous andvaried and are selected according to the initiator used and the othercomponents of the composition of the invention. Generally, the solventsmay be alcohols, esters, ethers, ketones, traces of water andcarbonates.

The alcohols commonly used are paratolylethanol, isopropylbenzylalcohol, benzyl alcohol, methanol, ethanol, propanol, isopropanol andbutanol. The ethers commonly used are methoxy-2-ethanol,ethoxy-2-ethanol, diethylene-glycol. The conventional esters aredibutylmaleate, dimethylethylmalonate, methyl salycilate, dioctyladipate, butyl tartrate, ethyl lactate, n-butyl lactate, isopropyllactate. Other solvents which may be used for the initiator bath andfalling in the other categories of solvents mentioned hereinbefore areacetonitrile, benzonitrile, acetone, cyclohexanone and tetrahydrofuran.

Furthermore, from among the solvents which may be used to dissolve theinitiators), certain types of proton donor organic solvents and certaintypes of hydroxylated carboxylic acid esters also have the property ofsignificantly improving their performance in terms of reactivity andkinetics.

As mentioned hereinbefore, in solution, the initiator claimed accordingto the invention can tend toward a solvated form. The various forms cancoexist within the solvent under the influence of an equilibrium.Examples of these salvation phenomena include, in particular

The present invention also extends to the solvated forms of the claimedinitiators.

According to another of its aspects, the present invention relatessecondly to polymerisable and/or cross-linkable compositions containingat least one polymerisable and/or cross-linkable polyorganosiloxane-typemonomer, oligomer and/or polymer carrying functional groups, aneffective quantity of at least one initiator of the type correspondingto the invention and described hereinbefore, optionally a polymerisationand/or cross-linking accelerator and optionally again one or moreadditives selected from among those generally known in the applicationsfor which these compositions are intended.

Effective quantity of initiator according to the invention means anadequate quantity to initiate polymerisation and/or cross-linking. Thisquantity is generally between 0.0001 and 5 parts by weight, usuallybetween 0.001 and 0.5 parts by weight in order to polymerise and/orcross-link 100 parts by weight of the dry substance inpolyorganosiloxane monomers, oligomers and/or polymers withorganofunctional groups.

As mentioned hereinbefore, the claimed initiator may be present in thepolymerisable and/or cross-linkable composition in association with aconventional initiator such as, in particular, a cationicphotoinitiator. Suitable conventional photoinitiators include, inparticular, those described in the patent EP 562 897. They may also becorresponding iodonium or sulphonium salts of hexafluorophosphate orhexafluoro-antimonate.

In this type of association, the two types of initiator are used in aproportion of 0.01 to 5 parts by weight in the case of thephotoinitiator and 1×10⁻⁵ to 5 parts by weight in the case of theclaimed initiator, preferably 1×10⁻⁴ to 1×10⁻² in the case of theinitiator claimed for polymerisation and/or cross-linking per 100 partsby weight of polyorganosiloxane-type polymerisable and/or cross-linkablemonomer(s), oligomer(s) and/or polymer(s) carrying functional groups.

Photocross-linkable coatings are thus obtained cationically, whichdevelop few interactions with adhesives and in particular with acrylicadhesives.

The claimed polymerisable and/or cross-linkable composition ispreferably based on polyorganosiloxane-type monomer(s) and/oroligomer(s) and/or polymer(s) consisting of units of formula (II) andterminated by units of formula (III) or cyclic groups consisting ofunits of formula (II) shown hereinafter:

in which

the symbols R¹ and R² are similar or different and represent:

a linear or branched alkyl radical containing 1 to 8 carbon atoms,optionally substituted by at least one halogen, preferably fluorine, thealkyl radicals preferably being methyl, ethyl, propyl, octyl and3,3,3-trifluoropropyl,

a cycloalkyl radical containing between 5 and 8 cyclic carbon atoms,optionally substituted,

an aryl radical containing between 6 and 12 carbon atoms which may besubstituted, preferably phenyl or dichlorophenyl,

an aralkyl portion having an alkyl portion containing between 5 and 14carbon atoms and an aryl portion containing between 6 and 12 carbonatoms, optionally substituted on the aryl portion by halogens, alkylsand/or alkoxyls containing 1 to 3 carbon atoms,

the symbols Z are similar or different and represent:

an R¹ and/or R² group,

a hydrogen radical,

and/or a cross-linkable organofunctional group, preferably anepoxy-functional, oxetane-functional, dioxolane-functional and/oralkenylether-functional group, bound to the silicone of thepolyorganosiloxane via a divalent radical containing 2 to 20 carbonatoms and possibly containing at least one heteroatom, preferablyoxygen,

wherein at least one of the symbols Z represents a cross-linkablefunctional organic group.

According to an advantageous variant of the invention, thepolyorganosiloxanes used contain 1 to 10 organofunctional groups permacromolecular chain. For an epoxy functional group, this corresponds toepoxide contents varying from 20 to 2,000 molar meq/100 g ofpolyorganosiloxane.

The linear polyorganosiloxanes may be oils having dynamic viscosity at25° C. of approx. 10 to 10,000 mPa.s at 25° C., generally of approx. 20to 5,000 mPa.s at 25° C. and even more preferably of 20 to 600 mPa.s at25° C. or gums having a molecular mass of approx. 1,000,000.

If cyclic polyorganosiloxanes are used, they consist of units (II) whichmay be, for example, of the dialkylsiloxy or alkylarylsiloxy type. Thesecyclic polyorganosiloxanes have a viscosity of approx. 1 to 5,000 mPa.s.

Examples of divalent radicals binding an organofunctional group of theepoxy and/or oxetane type include those of the following formulae:

Examples of organofunctional groups of the alkenyl ether type includethose contained in the following formulae:

in which.

n′ represents 0 or 1 and n″ represents an integer between 1 and 5

R³ represents

a linear, branched or cyclic C₁ to C₁₂, optionally substituted, alkyleneradical, or

a C₅ to C12 arylene radical, preferably phenylene, optionallysubstituted, preferably by one to three C₁ to C₆ alkyl groups,

R⁴ represents a linear or branched C₁ to C₆ alkyl radical.

Examples of dioxolane groups include those contained in the followingformulae:

The epoxy or alkenylether-functional polyorganosiloxanes are generallyin the form of fluids having a viscosity at 25° C. of 10 to 10,000 mm²/sand preferably 20 to 600 mm²/s.

The dynamic viscosity at 25° C. of all the silicones considered in thepresent description may be measured using a BROOKFIELD viscosimetercorresponding to AFNOR standard NFT 76 102 of February 1972.

This type of compound is described, in particular, in the patentsDE-A-4.009.889; EP-A-396.130; EP-A-355.381; EP-A-105.341;FR-A-2.110.115; FR-A-2.526.800.

The alkenylether-functional polyorganosiloxanes may be prepared byhydrosilylation reaction between the oils containing Si—H units andvinyloxy-functional compounds such as allylvinylether,allylvinyloxyethoxybenzene; etc.

Epoxy-functional polyorganosiloxanes may be prepared by hydrosilylationreaction between oils containing Si—H units and epoxy-functionalcompounds such as vinyl-4 cyclohexeneoxide, allylglycidylether, etc.

The oxetane-functional polyorganosiloxanes may be prepared byhydrosilylation of unsaturated oxetanes or condensation of oxetanescontaining a hydroxy-function.

The dioxolane-functional polyorganosiloxanes may be prepared byhydrosilylation of unsaturated dioxolanes.

Polyorganosiloxanes of which the units of formulae (II) and/or (III)comprise at least one phenyl, tolyl or dichlorophenyl radical as radicalR¹ are quite particularly suitable for the invention.

The silicones best suited for the subject of the invention are describedhereinafter and comprise at least one epoxide, alkenylether or oxetanegroup.

In the following formulae, X may represent an alkyl, cyclohexyl;trifluoropropyl; perfluoroalkyl; alkoxy or hydroxypropyl group, R a C₁to C₁₀ alkyl, C₁ to C₁₀ cyclohexyl, trifluoropropyl or perfluoroalkylradical and (0≦a≦1000); (1≦b≦1000).

According to an interesting disposition of the second subject of theinvention, the polymerisable and/or cross-linkable composition is basedon *polyorganosiloxane-type monomer(s) and/or oligomer(s) and/orpolymer(s) such as those defined hereinbefore and on organic-type, inparticular hydrocarbon-containing monomer(s), oligomer(s) or polymer(s).

In this instance, the following organic monomers, oligomers or polymersin which n can vary from 0 to 1,000 are particularly suitable for theinvention.

According to a third interesting disposition of the second subject ofthe invention, the polymerisable and/or cross-linkable composition isbased on polyorganosiloxane-type and optionally organic-type monomer(s)and/or oligomer(s) and/or polymer(s) in particularhydrocarbon-containing monomer(s) and/or oligomer(s) and/or polymer(s).

To use the initiators according to the invention, various sources ofheat may be used to carry out polymerisation and/or cross-linking of themonomers, oligomers and/or polymers. In the particular case where theinitiator according to the invention is used with a cationicphotoinitiator, the heat inherent in the irradiation used to activatesaid photoinitiator may be sufficient simultaneously to activate theclaimed initiator.

Conventionally, the compositions according to the invention can alsocomprise inter alia one or more additives selected as a function of theintended final application.

The additives may be, in particular, compounds possibly in the form ofpolymers containing mobile hydrogens such as alcohols, glycols andpolyols which are useful for improving the flexibility of the materialwhich has hardened after polymerisation and/or cross-linking; theseinclude, for example, polycaprolactone polyols, in particular thepolymer initially obtained from2-ethyl-2-(hydroxymethyl)-1,3-propane-diol and 2-oxepanone such as theproduct TONE POLYOL-301 sold by UNION CARBIDE or the other industrialpolymers TONE POLYOL 201 and TONE POLYOL 12703 from UNION CARBIDE.Further suitable additives include long chain alkyl diacids, the fattyesters of epoxidised or non-epoxidised unsaturated acids, for exampleepoxidised soya oil or epoxidised linseed oil, epoxidised 2-ethylhexylester, 2-ethylhexyl epoxy stearate, octyl epoxy stearate, epoxidisedacrylic esters, epoxidised acrylates of soya oil, acrylates ofepoxidised linseed oil, glycolpolypropylene diglycidyl ether, long chainaliphatic epoxides, etc.

This additive may be, in particular, a stabilisation additive. It isgenerally an aminated agent containing at least one amine of which theboiling point is higher than 150° C. and preferably higher than 200° C.This amine may be a secondary amine or a tertiary amine.

In particular, the amines described in WO 98/07798 may be used.

It should be noted that the majority of hindered amines used asstabilisers to light (“HALS” type) have been found to be very goodcandidates for meeting the requirements of the stabilisers used in thescope of the invention even though their intrinsic property of stabilityto light is not directly related to the mode of action of thestabilising aminated agents of the compositions according to theinvention. In this regard, it is possible to use the various types ofhindered amines in the documents EP 162 524 and EP 263 561.

Numerous types of commercially available hindered amines have given goodresults, in particular:

the TINUVIN products sold by CIBA GEIGY, in particular the productsTINUVIN 144 and TINUVIN 765 described hereinafter,

the CYAGARD products sold by CYTEC, in particular the product CYAGARD UV1164L, and

the SANDUVAR products, in particular the product SANDUVAR 3055,described hereinafter and sold by SANDOZ.

Other types of amines corresponding to the following formulae are alsogood candidates for use in the compositions of the invention; by way ofexample, the structure of some of these amines is given hereinafter:

The percentage of aminated agent generally used by weight relative tothe total weight of the silicone matrix is between 1 and 1,000 ppm andpreferably between 10 and 100 ppm. In the case of HALS type aminatedagent, the quantity is approx. 20 to 100 ppm.

The compositions according to the invention may also contain otheringredients such as adhesion modulators for increasing or reducing theforces of adhesion obtained from the polyorganosiloxane alone (siliconelinear resins or polymers carrying vinyl, epoxy, vinyl ether, alcoholfunctions), pigments, photosensitisers, fungicidal, bactericidal andanti-microbial agents, corrosion inhibitors, etc.

Whatever the nature of the polymerisable matrix, these may also be, forexample: fillers such as, in particular, synthetic fibres, titaniumdioxide, silica from precipitation or combustion; soluble dyes;oxidation and corrosion inhibitors; organosilicon or other adhesionmodulators; fungicidal, bactericidal, anti-microbial agents; and/or anyother material which does not interfere with the activity of theinitiator.

The present invention also relates to resins or polymers obtainable fromthe above-described compositions.

In the particular case where the compositions are used to prepare dentalcompositions, various types of fillers may be used. The fillers areselected as a function of the final use of the dental composition: theyaffect significant properties such as, the appearance, the penetrationof UV radiation and the mechanical and physical properties of thematerial obtained after cross-linking and/or polymerisation of thedental composition.

Suitable reinforcing fillers include treated or untreated pyrogenatedsilica fillers, amorphous silica fillers, quartz, glass or non-vitreousfillers based on zirconium, barium, calcium, fluorine, aluminium,titanium, zinc oxides, borosilicates, aluminosilicates, talcum,spherosil, ytterbium trifluoride, polymer-based fillers in the form ofcrushed powder such as inert or functionalised polymethylmethacrylates,polyepoxides or polycarbonates. Examples include:

LUXASELF inert fillers based on polymethylmethacrylate from the companyUGL which contain pink pigment and may be used in the dental field,

hexamethyldisilazane-treated fumed silica fillers having a specificsurface area of 200 m²/g,

untreated fumed silica charges (“aerosil” AE200 sold by DEGUSSA).

The fillers, and in particular the silica fillers, may be treated priorto use at 120° C. with a quantity smaller than 10% p/p of siliconecomprising at least one unit of formula

P—Si—(R⁵)_(a′)—O_((3-1′)/2)

wherein P, which may be the same or different, is an organic substituentcontaining at least one reactive epoxy and/or alkenyl ether and/oroxetane and/or dioxolane and/or carbonate function,

R⁵, which may be the same or different, is a C₁ to C₆ alkyl, cycloalkyl,aryl, vinyl, hydrogen, alkoxy, preferably lower alkyl radical,

a′=0, 1, 2 or 3,

with at least one silicon atom.

The polymer described hereinafter wherein P=epoxide and P=trialkoxysilylmay be mentioned as an example

The dental compositions according to the invention may be used fornumerous dental applications and in particular in the field of dentalprostheses, in the field of dental restoration and in the field oftemporary teeth.

Advantageously, in dental use, the compositions according to theinvention allow rapid setting at ambient temperature and a significantreduction in the phenomenon of shrinkage normally observed withconventional silicone compositions.

In the field of dental prostheses, the dental composition according tothe invention is preferably in the form of a single product containingthe various components (“monocomponent”) and this facilitates the usethereof. If necessary, this product may be stabilised by organicderivatives containing amine functions in accordance with the teachingof the document WO 98/07798.

The product may be deposited by means of a syringe directly onto theplaster model or in a mould. It is then polymerised (polymerisation bypossible successive layers) by means of a UV lamp (visible lightspectrum 200 to 500 nm). An aesthetic dental prosthesis is generallyproduced in 10 to 15 minutes.

It should be noted that the products obtained from the dentalcomposition according to the invention are not porous. Thus, afterpolishing with a felt brush, for example, if necessary, the surfaces ofthe dental prostheses obtained is smooth and shiny and therefore doesnot necessitate the use of varnish. Applications in the field of dentalprostheses are essentially those of complete denture.

In the field of dental restoration, the dental composition according tothe invention may be used as material for filling front and back teethin different colours (for example “VITA”), which is quick and easy touse.

As the dental composition is non-toxic and may be polymerised in thicklayers, it is not essential to polymerise the material in successivelayers. Generally, a single injection of the dental composition willsuffice.

The preparations for dental prostheses and for restoration materials arecarried out by conventional methods in the art.

With regard to the other applications, the compositions according to theinvention may be used as they are or in solution in an organic solvent.They are useful in the field of non-adhesive coatings on cellulosecontaining materials, paints, the encapsulation of electric andelectronic components, coatings for textiles and for the cladding ofoptical fibres.

They are of particular interest when used as such to make a materialnon-adhesive, such as metal sheets, glass, plastics material or paper toother materials to which they normally adhere. The compositionadvantageously has a viscosity not exceeding 5,000 mPa.s, preferably notexceeding 4,000 mpa.s at 25° C.

The invention therefore also relates to a process for making articles(for example sheets) non-adhesive to surfaces to which they normallyadhere, the process being characterised in that it involves applying aquantity of composition of the invention generally of between 0.1 and 5g per m² of surface to be coated and cross-linking or polymerising thecomposition by exposing it to a source of heat.

This invention also extends to coatings derived from the claimed resinand/or polymer compositions. The coating may be of the varnish,adhesive, non-adhesive type and/or an ink. Silicone coatings may also beobtained in the field of encapsulation of electronic components orcladdings for optical fibres.

The solvent-free, in other words undiluted, compositions are appliedusing devices capable of depositing small quantities of liquidsuniformly. The device known as “sliding Helio” comprising, inparticular, two superimposed cylinders may be used for this purpose: therole of the lowest cylinder immersed in the coating tank containing thecomposition is to impregnate the highest cylinder in a very thin layer,the role of the highest cylinder therefore being to deposit the desiredquantities of composition with which it is impregnated on the paper,this dosage being obtained by adjusting the respective speed of the twocylinders which rotate in opposite directions to one another.

The quantities of compositions deposited on the substrates vary andusually range between 0.1 and 5 g/m² of treated surface. Thesequantities depend on the nature of the substrates and the desirednon-adhesive properties. They are usually between 0.5 and 1.5 g/m² inthe case of non-porous substrates.

The present invention also relates to the use of a compound of generalformula I as defined hereinbefore as a heat-activated polymerisationand/or cross-linking initiator for polyorganosiloxane-type monomers,oligomers and/or polymers with organofunctional groups, in particular asdefined hereinbefore.

The present invention also relates to the articles (for example sheets)consisting of a solid material (metal, glass, plastics material, paper,etc.) of which at least one surface is coated with the above-mentionedthermally-cross-linked composition.

The following examples are given as an illustration and cannot beconsidered as a limit to the scope and essence of the invention.

EXAMPLE 1

The polymer (S1)

is used in a proportion of 10 g such that a=80; b=7.

This polymer is or is not stabilised by 50 ppm of a hindered amine usedas light stabiliser, namely TINUVIN 765®.

The initiator (C₆F₅)₃ B designated P1, 18% in solution in dibutylether,is added.

The concentration of the trispentafluorophenylborane is 0.18% insilicone.

The setting time of the silicone polymer after mixing with stirring isrecorded. The gel time corresponding to passage from the liquid state tothe solid state is less than 30 seconds at 25° C. and found to be 10 s.

EXAMPLE 2

The same experiment as in example 1 is carried out while adding theinitiator P1 in a proportion of 9% in butylether, i.e. 0.09% insilicone.

The gel time is also found to be 13 seconds.

EXAMPLE 3

The same experiment as in example 1 is carried out while introducing theinitiator P1 in a proportion of 9% in isopropanol, i.e. 0.08% insilicone.

The gel time, which is 3 minutes at ambient temperature, is recorded.

EXAMPLE 4

The same reaction as in example 1 is carried out but while introducingthe initiator P1 in a proportion of 270 ppm in the polymer (S1) in theform of an 18% solution in butylether. The mixture is applied in a thinlayer using a calibrated Meyer rod 0 so as to deposit 1.5 to 2 g/m² on acoated paper (Lohjan).

The shelf life in a stirred pot is 1 minute.

The coating polymerises in less than 30 s at 100° C. leading to across-linked coating exhibiting rub-off (gumming to touch).

The coating which has polymerised in one minute at 100° C. leads to across-linked layer exhibiting no rub-off and appears to be perfectlypolymerised.

The polymerised layers obtained are then provided with an acrylicadhesive of the TESA4970® type. The complexes are subjected to apressure of 70 g/cm² and the detachment forces are measured after 20 hat 70° C. by the FINAT No. 10 test and after 7 days at 70° C.

The detachment forces obtained by peeling at 180° C. on a dynamometerare lower than 20 g/cm.

EXAMPLE 5

The same reaction as in example 1 is carried out but while introducingthe initiator P1 in a proportion of 900 ppm in the polymer (S1) in theform of a 9% solution in isopropanol. The mixture is applied in a thinlayer using a calibrated Meyer rod 0 so as to deposit 1.5 to 2 g/m² on aLohjan coated paper.

The shelf life in a stirred pot is 3 minutes.

The coating polymerises in less than 10 s at 100° C. leading to across-linked layer which has no rub-off and appears to be perfectlypolymerised.

The polymerised layers obtained are then provided with an acrylicadhesive of the TESA4970 type for 15 minutes. The complexes aresubjected to a pressure at 70 g/m² and the detachment forces aremeasured after 20 h at 70° C.

The detachment forces obtained by peeling at 180° of the adhesive on adynamometer are lower than 50 cN/inch.

EXAMPLES 6 to 15

These examples show that the association of a trisarylborane with acationic photoinitiator based on diaryliodonium or triarylsulfonium saltproduces an increase in reactivity and lead to complete polymerisation.

The initiator P1 used is

The photoinitiator PI used corresponds to the formula

The silicone polymer used corresponds to the general formula

In the Case of Examples 6 to 10

The polymer (S1a) is used in a proportion of 950 g such that a=80; b=7

This polymer is stabilised by 50 ppm of HALS (TINUVIN 765)

A polymer (S1b) is also used in a proportion of 50 g such that a=220;b=3.8

The initiator P1 is added in a proportion of 0, 10, 25, 50 or 100 ppm tothe two polymers S1a and S1b from five solutions of photoinitiator PI ina proportion of 18% in isopropanol with added initiator P1.

Ex. 6: Solution 1 containing 0% of P1 and 18% of PI: 25 g of solution 1is added

Ex. 7: Solution 2 containing 0.04% of P1 and 18% of PI: 25 g of solution2 is added

EX. 8: Solution 3 containing 0.1% of P1 and 18% of PI: 25 g of solution3 is added

Ex. 9: Solution 4 containing 0.2% of P1 and 18% of PI: 25 g of solution4 is added

Ex. 10: Solution 5 containing 0.4% of P1 and 18% of PT: 25 g of solution5 is added

The initiators in the silicone formulation are mixed using a Tripalemixer for half an hour at ambient temperature. The bath is stable formore than 24 hours.

The silicone is then applied to a polyester terephthalate film usingcoating rollers so that the coating is a layer of 1 g/m².

The speed of travel of the film is 100 m/min.

The film is exposed to a UV lamp having a power of 120 W/cm and anadhesive based on butyl acrylate in emulsion from the RHODOTAK range(RHODOTAK315P®) is applied immediately after exposure. The adhesive isdried at 110° C. in an oven either “in line” at the speed of travel ofthe film (100 m/min) or “off-line” independently on another line at amuch faster speed of travel.

After the adhesive on the surface of the silicone coating has dried, theadhesive is transferred to a vellum paper using a transfer roller. Aself-adhesive complex of which the detachment forces are measured duringthe period after compression of the labels under 70 g/cm² is thusobtained. The test is standardised and corresponds to the FINATstandards

FINAT3=20 h at 20° C.

FINAT10=20 h at 70° C. which simulates natural ageing for 3 months at20° C.

In the Case of Examples 11 to 15

The same coatings as in examples 6 to 10 are produced except that thesilicone deposit is 1.5 g/m² in the case of a rougher substrate based oncoated paper (Lopabase w67) produced by Lohjan.

The same measurements of detachment forces are taken in examples 11 to15.

The results are expressed in cN/inch and presented in Table I.

TABLE I F3 F10 Example PI (ppm) P1 (ppm) cN/inch cN/inch 6 4300 0 5.0861 7 4300 10 4.31 55.9 8 4300 25 4.57 50.8 9 4300 50 7.7 40.6 10 4300100 5.08 30.5 11 4300 0 7.62 155 12 4300 10 4.57 88.9 13 43G0 25 7.6296.5 14 4300 50 5.08 83.8 15 4300 100 0.35 55.9

Furthermore, the detachment forces evolve less with this type ofadhesive which is reputed to be one of the most aggressive and isapplied in an aqueous phase. Photocross-linkable coatings are thusobtained cationically and rarely interact with the adhesives, inparticular with acrylic adhesives. The detachment force decreases as theinitiator 1 is added.

EXAMPLE 16

Example 10 is repeated while reducing the quantity of photointiator PIby two and keeping 100 ppm of trisarylborane in the final mixture.

Values equivalent to the test 6 without borane are found after measuringthe detachment forces. The gain in photoinitiator is thereforemultiplied by two.

TABLE II F3 F10 Example cN/inch cN/inch 16 5.08 55.9

What is claimed is:
 1. A polymerizable and/or cross-linkable compositionwhich comprises at least one polyorganosiloxane type monomer, oligomerand/or polymer with organofunctional groups, and an effective quantityof at least one heat-activated initiator comprising a boron derivativeof formula (I) (A)_(x)B(R′)_(y)  (I) wherein the symbols R′ are the sameor different and represent a linear or branched C₁-C₁₂ alkyl or alkenylradical, optionally substituted by at least one electron-withdrawinggroup, a linear or branched C₁-C₁₂ alkoxy radical, optionallysubstituted by at least one electron-withdrawing group, a phenyl radicalsubstituted by at least one electron-withdrawing group, an aryl radicalcontaining at least two aromatic rings, optionally substituted by atleast one electron-withdrawing group, a —C₂H₄—Si(Q)₃ radical with thesymbols Q being the same or different and representing a C₁ to C₁₀ alkylor alkoxy group or a siloxane oligomer with less than 10 silicone atoms,optionally substituted, by a radical of formula B(R′)₂ with R′ asdefined above, or two R′ groups may be bound to one another to form,with the boron atom to which they are bound, a cycle containing 5 or 10atoms wherein said cycle is saturated, unsaturated, bridged or aromaticand optionally comprises one or more heteroatoms selected from the groupconsisting of oxygen, nitrogen and boron atoms, wherein the boron atompresent in said cycle is optionally substituted by a radical as definedfor A or R′ in general formula I, the symbols A are independent of oneanother and represent: a hydrogen atom, a halogen atom, or a hydroxylradical, x represents 0 or the integer 1 or 2 and y represents aninteger 1, 2 or 3 wherein the sum of x+y is equal to 3 and its solvatedforms, and the group R′ together with the group A contributes to a σ_(p)at least equal to that of 3 (C₆H₄F) radicals.
 2. The composition ofclaim 1, wherein at least one of the symbols R′ represents a phenyl oraryl radical.
 3. The composition of claim 1, wherein said initiator hasthe general formula (Ia)

wherein n represents an integer between 1 and 3 and m an integer between0 and 2 wherein the sum of n and m is equal to 3, the symbols Y are thesame or different and represent a hydrogen atom, a hydroxyl group, ahalogen atom, a linear or branched C₁-C₁₂ alkyl or alkenyl radical,substituted by at least one halogen atom element, a linear or branchedC₁ to C₁₂ alkoxy radical, optionally substituted by at least one halogenatom element, a —C₂H₄—Si(Q)₃ wherein Q represents a C₁ to C₁₀ alkyl oralkoxy group or a siloxane oligomer with less than 10 silicone atoms,optionally substituted by a radical of formula B(R′)₂ wherein R′ is asdefined above, or two groups Y optionally may be bound so as to form,with the boron atom to which they are bound, a C₅ to C₁₀ cycle whereinsaid cycle is saturated, unsaturated, bridged or aromatic and maycomprise one or more heteroatoms selected from the group consisting ofoxygen, nitrogen and boron atoms, wherein the boron atom present in saidcycle optionally is substituted by a radical as defined for Y in generalformula (Ia) and the symbols X′ are the same or different and representa halogen atom, a linear, branched, mono- or polycyclic, saturated,unsaturated or aromatic C₁ to C₁₂ hydrocarbon radical optionallysubstituted by at least one halogen atom element or a linear orbranched, mono-, poly or perhalogenated C₁ to C₁₂ alkyl radical, and theindices p are the same or different and represent an integer between 0and
 5. 4. The composition of claim 1, wherein said initiator is selectedfrom the following compounds:


5. The composition of claim 1, wherein said initiator is used insolution in a solvent.
 6. The composition of claim 1, wherein theinitiator is used in a proportion of 0.0001 to 5 parts by weight per 100parts by weight of the dry substance in polyorganosiloxane typemonomers, oligomers and/or polymers with organofunctional groups.
 7. Thecomposition of claim 1, wherein the polyorganosiloxane type monomers,oligomers and/or polymers contain epoxide, oxetane, dioxolane and/oralkenylether groups as organofunctional groups.
 8. The composition ofclaim 1, wherein the type polyorganosiloxane monomers, oligomers and/orpolymers with organofunctional groups comprise units of formula (II) andare terminated by units of formula (III) or cyclic groups comprisingunits of formula (II) shown below:

wherein the symbols R¹ and R² are similar or different and represent: alinear or branched alkyl radical containing 1 to 8 carbon atoms,optionally substituted by at least one halogen, a cycloalkyl radicalcontaining between 5 and 8 cyclic carbon atoms, optionally substituted,an aryl radical containing between 6 and 12 carbon atoms optionallysubstituted, an aralkyl radical having an alkyl portion containingbetween 5 and 14 carbon atoms and an aryl portion containing between 6and 12 carbon atoms, optionally substituted on the aryl portion byhalogens, alkyls and/or alkoxyls containing 1 to 3 carbon atoms, thesymbols Z are similar or different and represent: an R¹ and/or R² group,a hydrogen radical, and/or a cross-linkable organofunctional group boundto the silicone of the polyorganosiloxane via a divalent radicalcontaining 2 to 20 carbon atoms and optionally containing at least oneheteroatom, wherein at least one of the symbols Z represents across-linkable functional organic group.
 9. The composition of claim 1,wherein the organofunctional groups are selected from the groupconsisting of:

wherein n′ represents 0 or 1 and n″ represents an integer between 1 and5 R³ represents a linear, branched or cyclic C₁ to C₁₂, optionallysubstituted, alkylene radical or an optionally substituted C₅ to C₁₂arylene radical, and R⁴ represents a linear or branched C₁ to C₆ alkylradical.
 10. The composition of claim 1, wherein at least one of thesymbols R′ represents a phenyl, tolyl or dichlorophenyl radical.
 11. Thecomposition of claim 1, wherein it further comprises a cationicphotoinitiator.
 12. Resin comprising the composition of claim
 1. 13.Polymer comprising the composition of claim
 1. 14. Coating comprisingthe resin according to claim
 12. 15. Coating according to claim 14,wherein said coating is a varnish, an adhesive coating, an anti-adhesivecoating and/or an ink.
 16. Dental composition comprising the compositionof claim
 1. 17. Dental composition according to claim 16, wherein it isa dental prosthesis or a dental restoration material.
 18. Object havingat least one surface coated with a resin according to claim
 12. 19. Amethod for polymerising and/or cross-linking a composition according toclaim 1 comprising the following steps of: (1) exposing the compositionto a source of heat, and (2) polymerising and/or cross-linking thecomposition.